A very basic program asked in written tests in interviews is Fibonacci series.
The series is 0,1,1,2,3,5,8,13,21....
Here in this article I am giving a detailed explanation of the code in each iteration.
The method is,
- class TestFibonnaci
- {
- public void Fibonacci()
- {
- int next = 1;
- int prev = 0;
- int fib = 0;
- while (fib < 20)
- {
- Response.Write(fib.ToString() + " ");
- prev = fib;
- fib = next;
- next = fib + prev;
-
- }
- }
- }
Next=1, prev=0, fib=0
Condition -is fib<20? Yes (0<20)
So Iteration One
Response.Write(fib.ToString()+" "); //Here it prints 0.
prev = fib; the variable prev gets assigned to 0 (i.e; prev=0)
fib = next ; the variable fib gets assigned to 1 (i.e; fib=1)
next = fib + prev; now next=0+1=1
Now }, means 1st iteration completed.
By the end of the first iteration, values of the variables prev, fib, next are as following,
Prev=0,
Fib=1,
Next=1
Now it checks the condional part.
is fib<20? Yes(1<20) true, so again enters into loop.
Now Second Iteration
Response.Write(fib.ToString()+" "); //Here it prints 1.
prev = fib; the variable prev gets assigned to 1 (i.e; prev=1)
fib = next ; the variable fib gets assigned to 1 (i.e; fib=1)
next = fib + prev; now next=1+1=2
Now }, means 2nd iteration completed.
By the end of the second iteration, values of the variables prev, fib, next are as follows,
Prev=1,
Fib=1,
Next=2
Now it checks condional part
is fib<20? Yes(1<20) true, so again enters into loop.
Now Third Iteration
Response.Write(fib.ToString()+" "); //Here it prints 1.
prev = fib; the variable prev gets assigned to 1 (i.e; prev=1)
fib = next ; the variable fib gets assigned to 2 (i.e; fib=2)
next = fib + prev; now next=2+1=3
Now }, means 3rd iteration completed.
By the end of the third iteration, values of the variables prev, fib, next are as following,
Prev=1,
Fib=2,
Next=3
Now it checks condional part
is fib<20? Yes(2<20) true, so again enters into loop.
Now Fourth Iteration
Response.Write(fib.ToString()+" "); //Here it prints 2.
prev = fib; the variable prev gets assigned to 2 (i.e; prev=2)
fib = next ; the variable fib gets assigned to 3 (i.e; fib=3)
next = fib + prev; now next=3+2=5
Now }, means 4th iteration completed.
By the end of the fourth iteration, values of the variables prev, fib, next are as following,
Prev=2,
Fib=3,
Next=5
Now it checks condional part
is fib<20? Yes(3<20) true, so again enters into loop.
Now Fifth Iteration
Response.Write(fib.ToString()+" "); //Here it prints 3.
prev = fib; the variable prev gets assigned to 3 (i.e; prev=3)
fib = next ; the variable fib gets assigned to 5 (i.e; fib=5)
next = fib + prev; now next=5+3=8
Now }, means 5th iteration completed.
By the end of the fifth iteration, values of the variables prev, fib, next are as following,
Prev=3,
Fib=5,
Next=8
Now it checks condional part
is fib<20? Yes(5<20) true, so again enters into loop.
Now Sixth Iteration
Response.Write(fib.ToString()+" "); //Here it prints 5.
prev = fib; the variable prev gets assigned to 5 (i.e; prev=5)
fib = next ; the variable fib gets assigned to 8 (i.e; fib=8)
next = fib + prev; now next=8+5=13
Now }, means 6th iteration completed.
By the end of 6th iteration, values of the variables prev, fib, next are as following,
Prev=5,
Fib=8,
Next=13
Now it checks condional part
is fib<20? Yes(8<20) true, so again enters into loop.
Now Seventh Iteration
Response.Write(fib.ToString()+" "); //Here it prints 8.
prev = fib; the variable prev gets assigned to 8 (i.e; prev=8)
fib = next ; the variable fib gets assigned to 13 (i.e; fib=13)
next = fib + prev; now next=13+8=21
Now }, means 7th iteration completed.
By the end of 7th iteration, values of the variables prev, fib, next are as following,
Prev=8,
Fib=13,
Next=21
Now it checks condional part.
is fib<20? Yes(13<20) true, so again enters into loop.
Now Eighth Iteration
Response.Write(fib.ToString()+" "); //Here it prints 13.
prev = fib; the variable prev gets assigned to 13 (i.e; prev=13)
fib = next ; the variable fib gets assigned to 21 (i.e; fib=21)
next = fib + prev; now next=21+13=34
Now }, means 8th iteration completed.
By the end of 8th iteration, values of the variables prev, fib, next are as following,
Prev=13,
Fib=21,
Next=34
Now it checks the condional part.
is fib<20? No(21<20) Falls, so CONDITION FAILS HERE , So, it does not enter into the loop.
So the final output is 0 1 1 2 3 5 8 13